Find the measure of the angle indicated

Of the ones listed here, the factor that had the greatest impact on the eventual destruction of native americans' ways of life was the development of the a) automobile. b) highway. c) railroad. d) steamboat.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Two airplanes start at the same place and travel in opposite directions,one at 395 miles per hour and the other at 422 miles per hour. how many hours will it take for the planes to be 2451 miles apart?